Thin film magnetic recording heads are used in the data storage industry for recording data onto narrow tracks on a magnetic medium. In a hard disk drive, a thin film head may be mounted to a head-gimbal-assembly which is used to position the head over concentric data tracks on a disk surface. Thin film heads may also be used with other magnetic medium types.
A thin film head may be produced by laminating one or more layers of magnetic film onto a substrate (made of Nixe2x80x94Zn ferrite or Alumina, for example). The completed head typically includes two conductive layers, called poles, separated by an insulating layer. The poles are conductively connected at one end and are separated by a thin insulating layer at another end so that the overall configuration has a somewhat horseshoe-like shape. Conductive wires are embedded within the insulating layer between the poles to form a coil that is used to read and write data to a magnetic medium.
During a write operation a magnetic flux is induced in the poles by an electrical current flowing through the coil. This magnetic flux flows through the connected conductive pole layers, but is impeded by their separation at the front gap. The pole separation at the front gap results in a discontinuity causing a magnetic field to protrude onto regions near the gap. This protruding field can be used to record data onto magnetic medium. In a digital storage device, changes in magnetic flux orientation caused by changes in the direction of current flow in the coil are used to write data to a magnetic medium. For example, a positive magnetic flux may be generated from a current flowing through the coil in a first direction, while a negative magnetic flux may be generated by changing the direction of the current. The positive and negative magnetic fluxes can be used to stored xe2x80x9c1xe2x80x9d and xe2x80x9c0xe2x80x9d bit values on the magnetic medium by vary the bias of magnetic dipoles in the medium. For example, a positive dipole bias may represent a xe2x80x9c1xe2x80x9d bit value while a negative bias may represent a xe2x80x9c0xe2x80x9d bit value.
Data may also be read from the magnetic medium using the same thin film head structure. When reading data, the write current is reduced or shut off so that the magnetic flux produced by the head is insufficient to change the orientation of magnetic dipoles in the medium. As the head passes over the medium, the magnetic flux produced by the dipoles in the medium induce a current in the coil windings that can be detected by read circuitry and decoded to determine a data stream.
In general, in one aspect, the invention features a method of forming a thin film magnetic recording head. The method includes forming a shared pole having a first pole tip, a first top pole segment having a second pole tip, and a write gap layer between the first pole tip and the second pole tip. The method also includes forming a write coil after forming the first top pole segment and then forming a second top pole segment that includes a connection to the first top pole segment and a connection to the shared pole.
Implementations may include one or more of the following features. An air bearing surface can be formed by lapping portions of the first and second pole tips. Forming the shared pole may include forming a first shared pole layer that includes the first pole tip and a second shared pole layer. At least a portion of the second top pole segment may be formed over a zero throat insulating layer that covers a portion of the write gap layer material. The zero throat insulating layer may increase separation between the shared pole and the first top pole segment. The write coil may be formed by depositing a write coil insulator layer over the shared pole, forming a first coil pattern over the write coil insulating layer, and depositing coil material on top of the first coil pattern. Forming the first coil pattern may include depositing a seed layer over the write coil insulator layer, coating the seed layer with a protective mask, removing the protective mask to expose a portion of the seed layer to form the first coil pattern, and depositing a conductive material on top of the exposed portions of the seed layer.
In general, in another aspect, the invention features a thin film magnetic head. The head includes a shared pole having a first pole tip, a first top pole segment having a second pole tip, a write gap layer positioned between the first pole tip and the second pole tip, a second top pole segment connected to the first top pole segment and to the shared pole, and a write coil positioned between the second top pole segment and the shared pole.
Implementations of the thin film magnetic head may include one or more of the following features. An insulating layer may separate the write coil from the shared pole and the first top pole segment. The second top pole segment may include a connection extending through a center of the write coil and connecting to the shared pole. The head may include a zero throat insulating layer having a region of increasing separation between the shared pole and the first top pole segment. A second write coil may be coupled to the write coil and positioned between the shared pole and the second top pole segment.
In general, in another aspect, the invention features a method of forming a thin file magnetic head. The method includes depositing a series of layers on a substrate to form a shared pole layer that includes a first pole tip, a top pole layer that includes a second pole tip, a gap layer between the first pole tip and the second pole tip, and a connection between the top pole layer and the shared pole layer. The method also includes means for forming a write coil between the top pole layer and the bottom pole layer after the first pole tip and second pole tip are formed.
Implementations may include one or more of the following advantages. A write head top pole tip may have a low aspect ratio, write head manufacturing yield may be improved, and manufacturing consistency between write heads may be improved. The details of one or more embodiments of the invention are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the invention will be apparent from the description and drawings, and from the claims.